/*
 * SKD CPNS Tryout — Design System
 * Swiss / International Typographic Style
 * Focus: clarity, content-first, long-term consistency.
 */

/* --------------------------------------------------------------------------
 * 1. DESIGN TOKENS
 * -------------------------------------------------------------------------- */

:root {
    /* Brand palette — muted teal, easy on the eyes */
    --color-brand: #3D6E6A;
    --color-brand-dark: #2B4F4C;
    --color-brand-light: #D0E2E1;
    --color-brand-subtle: #EBF3F2;

    /* Neutrals — warm and soft for long reading */
    --color-black: #1A1A1A;
    --color-white: #FFFFFF;
    --color-off-white: #F8F7F5;
    --color-cream: #F2F0EC;
    --color-gray-50: #F5F5F3;
    --color-gray-100: #EFEFED;
    --color-gray-200: #E0DFDC;
    --color-gray-300: #C8C7C4;
    --color-gray-400: #9C9B98;
    --color-gray-500: #737271;
    --color-gray-600: #525150;
    --color-gray-700: #3A3938;

    /* Accent — warm contrast to teal */
    --color-accent: #C4703C;
    --color-accent-light: #F5E6D8;

    /* Semantic */
    --color-success: #2D7A5F;
    --color-success-bg: #E8F5EE;
    --color-danger: #B83A3A;
    --color-danger-bg: #FCEAEA;
    --color-warning: #B5841C;
    --color-info: #3B6BA5;

    /* Typography */
    --font-sans: 'Inter', 'Helvetica Neue', Helvetica, Arial, sans-serif;
    --font-display: 'Space Grotesk', 'Inter', 'Helvetica Neue', sans-serif;
    --font-mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

    --text-xs: 0.6875rem;   /* 11px */
    --text-sm: 0.8125rem;   /* 13px */
    --text-base: 0.9375rem; /* 15px */
    --text-lg: 1.0625rem;   /* 17px */
    --text-xl: 1.25rem;     /* 20px */
    --text-2xl: 1.5rem;     /* 24px */
    --text-3xl: 2rem;       /* 32px */
    --text-4xl: 2.5rem;     /* 40px */
    --text-5xl: 3.25rem;    /* 52px */

    --leading-tight: 1.15;
    --leading-snug: 1.3;
    --leading-normal: 1.55;
    --leading-relaxed: 1.7;

    --tracking-tight: -0.02em;
    --tracking-normal: 0;
    --tracking-wide: 0.04em;
    --tracking-wider: 0.08em;

    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;
    --space-20: 5rem;
    --space-24: 6rem;

    /* Layout */
    --radius-sm: 0;
    --radius-md: 0;
    --radius-lg: 0;
    --container-max: 68rem; /* 1088px — tighter for better line lengths */

    /* Borders */
    --border-width: 1.5px;
    --border-color: var(--color-black);
    --border-muted: var(--color-gray-200);

    /* Shadows — minimal, used only when necessary */
    --shadow-sm: 0 1px 2px 0 rgb(17 17 17 / 0.04);
    --shadow-md: 0 2px 8px -2px rgb(17 17 17 / 0.08);

    /* Transitions */
    --transition-fast: 120ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 350ms ease;

    /* Focus ring */
    --focus-ring-width: 2px;
    --focus-ring-color: var(--color-brand);
    --focus-ring-offset: 3px;
}

/* --------------------------------------------------------------------------
 * 2. BASE STYLES
 * -------------------------------------------------------------------------- */

*,
*::before,
*::after {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    margin: 0;
    font-family: var(--font-sans);
    font-size: var(--text-base);
    line-height: var(--leading-normal);
    color: var(--color-black);
    background-color: var(--color-off-white);
}

/* --------------------------------------------------------------------------
 * ROADMAP — flowchart-style skill tree
 * -------------------------------------------------------------------------- */
.roadmap-page { max-width: 52rem; }

/* Vertical tree container */
.fc-tree {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
}

/* Section block */
.fc-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    max-width: 38rem;
}

/* Vertical connector line between nodes */
.fc-connector {
    width: 2px;
    height: 2rem;
    background: var(--color-gray-200);
}

/* Section header node */
.fc-node-section {
    --fc-accent: var(--color-brand);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.15rem;
    padding: var(--space-4) var(--space-6);
    background: var(--fc-accent);
    color: var(--color-white);
    text-align: center;
    width: 100%;
    max-width: 20rem;
}

.fc-section-twk .fc-node-section { --fc-accent: var(--color-brand); }
.fc-section-tiu .fc-node-section { --fc-accent: var(--color-accent); }
.fc-section-tkp .fc-node-section { --fc-accent: var(--color-info); }

.fc-node-tag {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    font-weight: 600;
    letter-spacing: var(--tracking-wider);
    opacity: 0.7;
}

.fc-node-section .fc-node-title {
    font-family: var(--font-display);
    font-size: var(--text-base);
    font-weight: 600;
}

.fc-node-sub {
    font-size: var(--text-xs);
    opacity: 0.6;
}

/* Branch: the skill list below a section */
.fc-branch {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    max-width: 28rem;
    padding-bottom: var(--space-8);
}

/* Each skill item: connector + node */
.fc-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
}

/* Horizontal connector (short vertical line from branch to node) */
.fc-connector-h {
    width: 2px;
    height: 1.25rem;
    background: var(--color-gray-200);
}

/* Child items indent slightly */
.fc-item-child {
    max-width: 22rem;
}

.fc-item-child .fc-connector-h {
    height: 0.75rem;
}

/* Parent node — group label, not interactive */
.fc-node-parent {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-3);
    width: 100%;
    padding: var(--space-2) var(--space-4);
    background: var(--color-cream);
    border: 1.5px solid var(--color-gray-300);
    text-align: center;
}

.fc-node-parent .fc-node-title {
    font-family: var(--font-display);
    font-size: var(--text-sm);
    font-weight: 700;
    color: var(--color-gray-700);
    letter-spacing: var(--tracking-wide);
    text-transform: uppercase;
}

.fc-node-parent .fc-node-meta {
    font-family: var(--font-mono);
    font-size: 0.6rem;
    color: var(--color-gray-400);
}

/* Skill node */
.fc-node-skill {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
    width: 100%;
    padding: var(--space-3) var(--space-4);
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    text-align: center;
    transition:
        border-color var(--transition-base),
        background-color var(--transition-base),
        box-shadow var(--transition-base);
}

.fc-node-skill:hover {
    border-color: var(--color-brand);
    background: var(--color-brand-subtle);
    box-shadow: 0 2px 8px -2px rgb(61 110 106 / 0.1);
}

.fc-node-skill .fc-node-title {
    font-family: var(--font-display);
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--color-black);
}

.fc-item-child .fc-node-skill .fc-node-title {
    font-size: var(--text-xs);
    font-weight: 500;
}

/* Progress meter inside skill node */
.fc-node-meter {
    display: block;
    height: 3px;
    background: var(--color-gray-100);
    overflow: hidden;
    margin: 0 auto;
    width: 80%;
}

.fc-node-meter-fill {
    display: block;
    height: 100%;
    background: var(--color-brand);
    transition: width var(--transition-slow);
}

/* Status-based meter colors */
.fc-status-mastered .fc-node-meter-fill { background: var(--color-success); }
.fc-status-needs\ practice .fc-node-meter-fill,
.fc-status-needs-practice .fc-node-meter-fill { background: var(--color-warning); }
.fc-status-ready\ for\ assessment .fc-node-meter-fill,
.fc-status-ready-for-assessment .fc-node-meter-fill { background: var(--color-brand); }

/* Mastered node gets a subtle green tint */
.fc-status-mastered .fc-node-skill {
    border-color: var(--color-success);
    background: var(--color-success-bg);
}

.fc-node-meta {
    font-family: var(--font-mono);
    font-size: 0.6rem;
    color: var(--color-gray-400);
    letter-spacing: var(--tracking-wide);
}

/* Mobile */
@media (max-width: 640px) {
    .fc-section { max-width: 100%; }
    .fc-branch { max-width: 100%; }
    .fc-item-child { max-width: 85%; }
    .fc-node-section { max-width: 100%; }
}

.profile-page { max-width: 68rem; }
.profile-card { display: flex; align-items: center; gap: 1rem; padding: 1.25rem; }
.profile-avatar { display: grid; place-items: center; width: 3.5rem; height: 3.5rem; flex: 0 0 3.5rem; background: var(--color-brand); color: var(--color-white); font: 700 1.5rem var(--font-display); text-transform: uppercase; }
.profile-name { margin: 0; font: 700 1.35rem var(--font-display); }
.profile-name-view { display: flex; align-items: center; gap: .55rem; }
.profile-edit-button { display: inline-grid; place-items: center; width: 1.8rem; height: 1.8rem; border: 1px solid var(--color-gray-200); background: var(--color-white); color: var(--color-gray-500); cursor: pointer; transition: color var(--transition-fast), border-color var(--transition-fast), background-color var(--transition-fast); }
.profile-edit-button:hover { border-color: var(--color-brand); background: var(--color-brand-subtle); color: var(--color-brand); }
.profile-edit-button [data-lucide] { width: .85rem; height: .85rem; }
.profile-email { margin: .2rem 0 0; color: var(--color-gray-500); font-size: .85rem; }
.profile-points { margin-left: auto; min-width: 5rem; text-align: right; }
.profile-points strong { color: var(--color-brand); font: 700 1.4rem var(--font-mono); }
.profile-identity { flex: 1; min-width: 0; }
.profile-name-form { display: flex; gap: .5rem; align-items: center; margin-top: .85rem; max-width: 32rem; }
.profile-name-form .form-input { min-width: 0; }
.profile-name-form [data-lucide] { width: .9rem; height: .9rem; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
@media (max-width: 480px) { .profile-card { align-items: flex-start; flex-wrap: wrap; } .profile-points { width: 100%; margin-left: 4.5rem; text-align: left; } }
.home-leaderboard-wrap { margin-top: 3rem; }
.home-leaderboard { width: 100%; margin: 0; padding: 1.25rem; }
.home-leaderboard-heading { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding-bottom: 1rem; border-bottom: 1px solid var(--color-gray-100); }
.home-leaderboard-heading h2 { margin: 0; font: 700 1.25rem var(--font-display); }
.home-leaderboard-heading p { margin: .25rem 0 0; color: var(--color-gray-500); font-size: .8rem; }
.home-leaderboard-rank { display: grid; place-items: center; min-width: 3.25rem; height: 3.25rem; background: var(--color-brand-subtle); color: var(--color-brand); font: 700 1.2rem var(--font-display); }
.home-leaderboard-list { margin-top: .5rem; }
.home-leaderboard-row { display: flex; align-items: center; gap: .75rem; padding: .75rem .5rem; border-bottom: 1px solid var(--color-gray-100); }
.home-leaderboard-row:last-child { border-bottom: 0; }
.home-leaderboard-row.is-current { background: var(--color-brand-subtle); }
.home-leaderboard-position { width: 1.5rem; color: var(--color-gray-400); font: 700 1rem var(--font-display); text-align: center; }
.home-leaderboard-name { flex: 1; font-weight: 500; }
.home-leaderboard-name small { color: var(--color-brand); font-size: .7rem; }
.home-leaderboard-row strong { color: var(--color-brand); font: 700 .9rem var(--font-mono); }
.progress-chart-header { display: flex; align-items: flex-end; justify-content: space-between; gap: 1rem; margin-bottom: 1.15rem; }
.progress-chart-card { margin-bottom: 3.5rem; }
.progress-chart-header strong { font-size: 1.05rem; }
.progress-chart-scale { color: var(--color-gray-400); font: .68rem var(--font-mono); }
.atcoder-chart { display: flex; gap: .7rem; min-height: 15rem; }
.atcoder-y-axis { display: flex; flex-direction: column; justify-content: space-between; padding: 0 0 .05rem; color: var(--color-gray-400); font: .65rem var(--font-mono); }
.atcoder-chart svg { width: 100%; min-width: 0; height: 15rem; overflow: visible; background: linear-gradient(180deg, rgba(61,110,106,.025), transparent); }
.chart-grid { stroke: var(--color-gray-200); stroke-width: 1; stroke-dasharray: 3 5; }
.chart-line { fill: none; stroke: var(--color-accent); stroke-width: 3; stroke-linejoin: round; stroke-linecap: round; }
.chart-point { fill: var(--color-white); stroke: var(--color-accent); stroke-width: 3; transition: r var(--transition-fast); }
.chart-point:hover { r: 6; }
.atcoder-x-axis { display: flex; justify-content: space-between; gap: .5rem; margin: .65rem 0 0 2rem; overflow: hidden; color: var(--color-gray-400); font: .63rem var(--font-mono); }
.atcoder-x-axis span { min-width: 0; white-space: nowrap; }
/* Recommendation block (used on progress page) */
.roadmap-recommendation { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 1rem 1.25rem; border-left: 4px solid var(--color-accent); }
.roadmap-recommendation strong { display: block; font-family: var(--font-display); }
@media (max-width: 480px) { .roadmap-recommendation { align-items: flex-start; flex-direction: column; } }

/* Keep every page usable on narrow screens without introducing a second nav system. */
@media (max-width: 640px) {
    .app-container { padding-left: 1rem; padding-right: 1rem; }
    .site-header .app-container { height: auto; min-height: 3.5rem; padding-top: .65rem; padding-bottom: .65rem; align-items: flex-start; gap: .75rem; }
    .site-logo { flex: 0 0 auto; gap: .5rem; }
    .site-logo-text { max-width: 7.5rem; font-size: .78rem; line-height: 1.15; }
    .site-nav { flex: 1 1 auto; min-width: 0; justify-content: flex-end; gap: 0; overflow-x: auto; scrollbar-width: none; }
    .site-nav::-webkit-scrollbar { display: none; }
    .site-nav > a { padding: .45rem .5rem; white-space: nowrap; font-size: .72rem; }
    .site-nav-divider { display: none; }
    .user-meta { max-width: 7rem; padding: .45rem .5rem; }
    .user-meta-name { max-width: 4.5rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: .72rem; }
    .user-meta-points { display: none; }
    .user-menu-dropdown { position: fixed; top: 3.65rem; right: 1rem; }
    #main-content { padding-top: 1.75rem; padding-bottom: 2rem; }
    .page-header { margin-bottom: 1.75rem; padding-bottom: .85rem; }
    .page-title { font-size: 1.8rem; }
    .hero-section { display: block; }
    .hero-title { font-size: clamp(2.25rem, 12vw, 3.25rem); }
    .hero-subtitle { max-width: none; }
    .hero-actions { align-items: stretch; flex-direction: column; }
    .hero-actions .btn, .hero-actions form { width: 100%; }
    .hero-actions form .btn { width: 100%; }
    .category-sidebar { margin-top: 2rem; }
    .card { max-width: 100%; }
    .card-body, .card-header { padding: 1rem; }
    .progress-chart-card, .home-leaderboard-wrap { margin-top: 1.5rem; margin-bottom: 2rem; }
    .progress-chart-header { align-items: flex-start; flex-direction: column; }
    .atcoder-chart, .atcoder-chart svg { height: 12rem; min-height: 12rem; }
    .atcoder-x-axis { margin-left: 1.75rem; font-size: .55rem; }
    .profile-card { padding: 1rem; }
    .profile-name { font-size: 1.1rem; }
    .home-leaderboard-heading { align-items: flex-start; flex-direction: column; }
    .home-leaderboard-row { gap: .5rem; font-size: .85rem; }
    .home-leaderboard-row strong { font-size: .72rem; }
    .home-pitch { gap: .5rem; }
    .table-responsive, .card:has(> table) { overflow-x: auto; -webkit-overflow-scrolling: touch; }
    table { min-width: 38rem; }
    .modal { width: calc(100vw - 2rem); max-height: calc(100vh - 2rem); }
    .pagination { max-width: 100%; overflow-x: auto; }
}

img, picture, video, svg {
    display: block;
    max-width: 100%;
}

a {
    color: inherit;
    text-decoration: none;
}

:focus-visible {
    outline: var(--focus-ring-width) solid var(--focus-ring-color);
    outline-offset: var(--focus-ring-offset);
}

::selection {
    background-color: var(--color-brand);
    color: var(--color-white);
}

/* Typography utilities */
.font-sans { font-family: var(--font-sans); }
.font-display { font-family: var(--font-display); }
.font-mono { font-family: var(--font-mono); }

/* --------------------------------------------------------------------------
 * 3. LAYOUT HELPERS
 * -------------------------------------------------------------------------- */

.app-container {
    width: 100%;
    max-width: var(--container-max);
    margin-left: auto;
    margin-right: auto;
    padding-left: var(--space-6);
    padding-right: var(--space-6);
}

@media (min-width: 1024px) {
    .app-container {
        padding-left: var(--space-10);
        padding-right: var(--space-10);
    }
}

.page-header {
    border-bottom: var(--border-width) solid var(--border-color);
    padding-bottom: var(--space-4);
    margin-bottom: var(--space-10);
}

.page-title {
    font-family: var(--font-display);
    font-size: var(--text-3xl);
    font-weight: 700;
    line-height: var(--leading-tight);
    letter-spacing: var(--tracking-tight);
}

.section-label {
    display: block;
    font-size: var(--text-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: var(--tracking-wider);
    color: var(--color-gray-400);
    margin-bottom: var(--space-2);
}

/* --------------------------------------------------------------------------
 * 4. NAVBAR
 * -------------------------------------------------------------------------- */

.site-header {
    position: sticky;
    top: 0;
    z-index: 40;
    background-color: var(--color-off-white);
    border-bottom: var(--border-width) solid var(--color-gray-200);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.site-header .app-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 3.5rem;
}

.site-logo {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

.site-logo-mark {
    width: 1.75rem;
    height: 1.75rem;
    background-color: var(--color-brand);
    color: var(--color-white);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-display);
    font-size: var(--text-sm);
    font-weight: 700;
    line-height: 1;
}

.site-logo-text {
    font-family: var(--font-display);
    font-size: var(--text-base);
    font-weight: 600;
    letter-spacing: var(--tracking-tight);
    color: var(--color-black);
}

.site-nav {
    display: flex;
    align-items: center;
    gap: var(--space-1);
}

.site-nav a {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-gray-500);
    padding: var(--space-2) var(--space-3);
    transition: color var(--transition-fast);
}

.site-nav a:hover {
    color: var(--color-black);
}

.user-menu { position: relative; }
.user-menu summary { list-style: none; cursor: pointer; }
.user-menu summary::-webkit-details-marker { display: none; }
.user-menu-chevron { width: 1rem; height: 1rem; color: var(--color-gray-400); transition: transform var(--transition-fast); }
.user-menu:hover .user-menu-dropdown,
.user-menu[open] .user-menu-dropdown { display: block; opacity: 1; visibility: visible; transform: translateY(0); }
.user-menu[open] .user-menu-chevron { transform: rotate(180deg); }
.user-menu-dropdown {
    position: absolute;
    top: calc(100% + .5rem);
    right: 0;
    z-index: 50;
    min-width: 9rem;
    padding: .35rem 0;
    border: 1px solid var(--color-gray-200);
    background: var(--color-white);
    box-shadow: var(--shadow-md);
    display: block;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-4px);
    transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
}
.user-menu-dropdown a,
.user-menu-dropdown button {
    display: block;
    width: 100%;
    padding: .6rem .85rem;
    border: 0;
    background: transparent;
    color: var(--color-gray-600);
    cursor: pointer;
    font: 500 var(--text-sm) var(--font-sans);
    text-align: left;
}
.user-menu-dropdown a:hover,
.user-menu-dropdown button:hover { background: var(--color-brand-subtle); color: var(--color-brand-dark); }
.btn [data-lucide], .inline-flex [data-lucide] { width: 1rem; height: 1rem; flex: 0 0 auto; }
.alert-icon [data-lucide], .toast-icon [data-lucide] { width: 1rem; height: 1rem; }

.site-nav-divider {
    width: 1px;
    height: 1rem;
    background-color: var(--color-gray-200);
    margin: 0 var(--space-2);
}

.user-meta {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    font-size: var(--text-sm);
}

.user-meta-name {
    font-weight: 500;
    color: var(--color-gray-700);
}

.user-meta-points {
    display: inline-flex;
    align-items: center;
    gap: var(--space-1);
    font-weight: 600;
    font-size: var(--text-xs);
    color: var(--color-brand);
    background-color: var(--color-brand-subtle);
    padding: 0.1875rem var(--space-2);
    letter-spacing: var(--tracking-wide);
}

/* --------------------------------------------------------------------------
 * 5. BUTTONS
 * -------------------------------------------------------------------------- */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: 0.5625rem var(--space-5);
    font-size: var(--text-sm);
    font-weight: 600;
    line-height: 1;
    text-align: center;
    white-space: nowrap;
    border: var(--border-width) solid transparent;
    cursor: pointer;
    transition:
        background-color var(--transition-base),
        border-color var(--transition-base),
        color var(--transition-base),
        box-shadow var(--transition-base);
}

.btn:hover {
    box-shadow: 0 1px 3px 0 rgb(0 0 0 / 0.08);
}

.btn:active {
    box-shadow: none;
}

.btn:disabled,
.btn[aria-disabled="true"] {
    opacity: 0.4;
    cursor: not-allowed;
    box-shadow: none;
}

.btn-primary {
    background-color: var(--color-brand);
    border-color: var(--color-brand);
    color: var(--color-white);
}
.btn-primary,
.btn-primary:visited,
.btn-primary:hover,
.btn-primary:active {
    color: var(--color-white);
}
.btn-google {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: .65rem;
    border: 1px solid #dadce0;
    background: #fff;
    color: #3c4043;
    box-shadow: 0 1px 2px rgb(60 64 67 / 0.12);
    font-weight: 600;
}
.btn-google:hover,
.btn-google:visited,
.btn-google:active { color: #202124; }
.btn-google:hover { border-color: #c5c7ca; background: #f8fafd; box-shadow: 0 2px 5px rgb(60 64 67 / 0.18); }
.google-mark { display: inline-grid; place-items: center; width: 1.35rem; height: 1.35rem; color: #4285f4; font: 700 1.15rem Arial, sans-serif; }

.btn-primary:hover {
    background-color: var(--color-brand-dark);
    border-color: var(--color-brand-dark);
}

.btn-secondary {
    background-color: var(--color-white);
    border-color: var(--color-black);
    color: var(--color-black);
}

.btn-secondary:hover {
    background-color: var(--color-black);
    color: var(--color-white);
}

.btn-ghost {
    background-color: transparent;
    border-color: transparent;
    color: var(--color-gray-600);
}

.btn-ghost:hover {
    background-color: var(--color-gray-100);
    color: var(--color-black);
    box-shadow: none;
}

.btn-sm {
    padding: var(--space-2) var(--space-4);
    font-size: var(--text-xs);
}

.btn-lg {
    padding: var(--space-4) var(--space-8);
    font-size: var(--text-base);
    font-weight: 600;
    letter-spacing: var(--tracking-wide);
}

/* --------------------------------------------------------------------------
 * 6. CARDS
 * -------------------------------------------------------------------------- */

.card {
    background-color: var(--color-white);
    border: var(--border-width) solid var(--color-gray-200);
    overflow: hidden;
    transition: border-color var(--transition-base);
}

.card:hover {
    border-color: var(--color-gray-300);
}

.card-header {
    padding: var(--space-3) var(--space-5);
    background-color: var(--color-black);
    color: var(--color-white);
}

.card-body {
    padding: var(--space-5) var(--space-6);
}

.card-muted {
    background-color: var(--color-gray-50);
}

/* SKD category cards — hero section */
.category-card {
    position: relative;
    display: flex;
    flex-direction: column;
    background-color: var(--color-white);
    border: var(--border-width) solid var(--color-gray-200);
    padding: var(--space-5) var(--space-5) var(--space-4);
    transition:
        border-color var(--transition-base),
        background-color var(--transition-base);
    overflow: hidden;
}

.category-card:hover {
    border-color: var(--color-brand);
    background-color: var(--color-brand-subtle);
}

.category-card-number {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    font-weight: 400;
    color: var(--color-gray-400);
    letter-spacing: var(--tracking-wide);
    margin-bottom: var(--space-3);
    transition: color var(--transition-base);
}

.category-card:hover .category-card-number {
    color: var(--color-brand);
}

.category-card-abbr {
    font-family: var(--font-display);
    font-size: var(--text-2xl);
    font-weight: 700;
    letter-spacing: var(--tracking-tight);
    line-height: 1;
    margin-bottom: var(--space-1);
    transition: color var(--transition-base);
}

.category-card:hover .category-card-abbr {
    color: var(--color-brand-dark);
}

.category-card-label {
    font-size: var(--text-xs);
    font-weight: 500;
    color: var(--color-gray-500);
    transition: color var(--transition-base);
}

.category-card:hover .category-card-label {
    color: var(--color-brand);
}

.category-card-action {
    font-size: var(--text-xs);
    font-weight: 600;
    color: var(--color-gray-300);
    margin-top: auto;
    padding-top: var(--space-3);
    border-top: 1px solid var(--color-gray-100);
    transition: color var(--transition-base), border-color var(--transition-base);
}

.category-card:hover .category-card-action {
    color: var(--color-brand);
    border-color: var(--color-brand-light);
}

.category-card-meta {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    padding-top: var(--space-3);
    border-top: 1px solid var(--color-gray-100);
    margin-top: auto;
    transition: border-color var(--transition-base);
}

.category-card:hover .category-card-meta {
    border-color: var(--color-brand-light);
}

.category-card-stat {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    color: var(--color-gray-400);
    letter-spacing: var(--tracking-wide);
    transition: color var(--transition-base);
}

.category-card:hover .category-card-stat {
    color: var(--color-brand);
}

/* --------------------------------------------------------------------------
 * 7. FORMS
 * -------------------------------------------------------------------------- */

.form-label {
    display: block;
    font-size: var(--text-sm);
    font-weight: 600;
    margin-bottom: var(--space-1);
    color: var(--color-black);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: var(--space-3) var(--space-4);
    font-size: var(--text-base);
    line-height: var(--leading-normal);
    color: var(--color-black);
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-300);
    transition:
        border-color var(--transition-base),
        box-shadow var(--transition-base);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    border-color: var(--color-brand);
    box-shadow: 0 0 0 3px var(--color-brand-light);
    outline: none;
}

.form-input::placeholder {
    color: var(--color-gray-400);
}

.form-hint {
    font-size: var(--text-sm);
    color: var(--color-gray-500);
    margin-top: var(--space-1);
}

.form-error {
    font-size: var(--text-sm);
    color: var(--color-danger);
    margin-top: var(--space-1);
}

/* --------------------------------------------------------------------------
 * 8. BADGES & STATUSES
 * -------------------------------------------------------------------------- */

.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.125rem var(--space-2);
    font-size: var(--text-xs);
    font-weight: 600;
    letter-spacing: var(--tracking-wide);
    border: 1px solid var(--color-gray-300);
    color: var(--color-gray-600);
    background-color: var(--color-white);
}

.badge-success {
    background-color: var(--color-success-bg);
    border-color: var(--color-success);
    color: var(--color-success);
}

.badge-danger {
    background-color: var(--color-danger-bg);
    border-color: var(--color-danger);
    color: var(--color-danger);
}

.badge-brand {
    background-color: var(--color-brand-subtle);
    border-color: var(--color-brand);
    color: var(--color-brand-dark);
}

/* --------------------------------------------------------------------------
 * 9. ALERTS
 * -------------------------------------------------------------------------- */

.alert {
    display: flex;
    align-items: flex-start;
    gap: var(--space-3);
    padding: var(--space-4);
    margin-bottom: var(--space-6);
    border: 1px solid var(--color-gray-200);
    background-color: var(--color-white);
    font-size: var(--text-sm);
}

.alert-icon {
    flex-shrink: 0;
    width: 1.25rem;
    height: 1.25rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: var(--text-xs);
}

.alert-content {
    flex: 1;
}

.alert-title {
    font-weight: 600;
    margin-bottom: 0.125rem;
}

.alert-message {
    color: var(--color-gray-600);
}

.alert-error {
    background-color: var(--color-danger-bg);
    border-color: var(--color-danger);
    color: var(--color-danger);
}

.alert-success {
    background-color: var(--color-success-bg);
    border-color: var(--color-success);
    color: var(--color-success);
}

.alert-info {
    background-color: var(--color-gray-50);
    border-color: var(--color-gray-300);
    color: var(--color-gray-700);
}

/* --------------------------------------------------------------------------
 * 10. UTILITY CLASSES
 * -------------------------------------------------------------------------- */

.text-muted { color: var(--color-gray-500); }
.text-brand { color: var(--color-brand); }
.bg-brand { background-color: var(--color-brand); }
.border-brand { border-color: var(--color-brand); }

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* Empty state */
.empty-state {
    text-align: center;
    padding: var(--space-12) var(--space-6);
    color: var(--color-gray-500);
}

/* --------------------------------------------------------------------------
 * 11. EXAM-SPECIFIC COMPONENTS
 * -------------------------------------------------------------------------- */

.question-box {
    border: var(--border-width) solid var(--color-gray-200);
    padding: var(--space-6);
}

@media (min-width: 1024px) {
    .question-box {
        padding: var(--space-8);
    }
}

.option-card {
    display: flex;
    align-items: flex-start;
    gap: var(--space-4);
    padding: var(--space-4);
    border: 1px solid var(--color-gray-200);
    background-color: var(--color-white);
    cursor: pointer;
    transition:
        background-color var(--transition-base),
        border-color var(--transition-base);
}

.option-card:hover {
    background-color: var(--color-brand-subtle);
    border-color: var(--color-brand-light);
}

.option-card input {
    margin-top: 0.125rem;
    accent-color: var(--color-brand);
}

.nav-grid-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    aspect-ratio: 1 / 1;
    border: 1px solid var(--color-gray-300);
    font-size: var(--text-xs);
    font-weight: 600;
    font-family: var(--font-mono);
    background-color: var(--color-white);
    color: var(--color-gray-500);
    transition:
        background-color var(--transition-fast),
        border-color var(--transition-fast),
        color var(--transition-fast);
}

.nav-grid-btn:hover {
    background-color: var(--color-gray-100);
    border-color: var(--color-gray-400);
    color: var(--color-black);
}

.nav-grid-btn.current {
    background-color: var(--color-brand);
    border-color: var(--color-brand);
    color: var(--color-white);
}

.nav-grid-btn.answered {
    background-color: var(--color-black);
    border-color: var(--color-black);
    color: var(--color-white);
}

.nav-grid-btn.review-btn {
    width: 2.5rem;
    height: 2.5rem;
    font-size: var(--text-xs);
}

.nav-grid-btn.review-btn.correct {
    background-color: var(--color-success);
    border-color: var(--color-success);
    color: var(--color-white);
}

.nav-grid-btn.review-btn.wrong {
    background-color: var(--color-danger);
    border-color: var(--color-danger);
    color: var(--color-white);
}

.nav-grid-btn.review-btn.unanswered {
    background-color: var(--color-gray-50);
    border-color: var(--color-gray-200);
    color: var(--color-gray-400);
}

/* --------------------------------------------------------------------------
 * 12. MODAL
 * -------------------------------------------------------------------------- */

.modal-overlay {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 50;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-4);
    background-color: rgba(17, 17, 17, 0.5);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-base), visibility var(--transition-base);
}

.modal-overlay.is-open {
    opacity: 1;
    visibility: visible;
}

.modal {
    width: 100%;
    max-width: 26rem;
    max-height: calc(100vh - var(--space-8));
    overflow-y: auto;
    background-color: var(--color-white);
    border: var(--border-width) solid var(--color-gray-200);
    box-shadow: 0 16px 48px -8px rgb(0 0 0 / 0.12);
    transform: translateY(-0.5rem);
    transition: transform var(--transition-base);
}

.modal-overlay.is-open .modal {
    transform: translateY(0);
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-4);
    padding: var(--space-4) var(--space-5);
    border-bottom: var(--border-width) solid var(--color-gray-200);
    background-color: var(--color-black);
    color: var(--color-white);
}

.modal-title {
    font-family: var(--font-display);
    font-size: var(--text-sm);
    font-weight: 600;
    letter-spacing: var(--tracking-wide);
}

.modal-close {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.75rem;
    height: 1.75rem;
    font-size: var(--text-base);
    line-height: 1;
    color: var(--color-gray-400);
    background: transparent;
    border: 1px solid transparent;
    cursor: pointer;
    transition: color var(--transition-fast);
}

.modal-close:hover {
    color: var(--color-white);
}

.modal-body {
    padding: var(--space-5);
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: var(--space-3);
    padding: var(--space-4) var(--space-5);
    border-top: 1px solid var(--color-gray-200);
}

/* --------------------------------------------------------------------------
 * 13. TOAST / NOTIFICATION
 * -------------------------------------------------------------------------- */

.toast-container {
    position: fixed;
    top: var(--space-4);
    right: var(--space-4);
    z-index: 70;
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
    max-width: 22rem;
    pointer-events: none;
}

.toast {
    display: flex;
    align-items: flex-start;
    gap: var(--space-3);
    padding: var(--space-3) var(--space-4);
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-200);
    box-shadow: 0 4px 16px -4px rgb(0 0 0 / 0.1);
    pointer-events: auto;
    animation: toast-in 0.2s ease forwards, toast-out 0.2s ease 4s forwards;
}

@keyframes toast-in {
    from {
        opacity: 0;
        transform: translateX(100%);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.toast.is-removing {
    animation: toast-out var(--transition-base) ease forwards;
}

@keyframes toast-out {
    from {
        opacity: 1;
        transform: translateX(0);
        max-height: 10rem;
        margin-bottom: 0;
        padding: var(--space-3) var(--space-4);
        border-width: 1px;
    }
    99% {
        opacity: 0;
        transform: translateX(100%);
        max-height: 0;
        margin-bottom: 0;
        padding: 0 var(--space-4);
        border-width: 0;
    }
    to {
        opacity: 0;
        transform: translateX(100%);
        max-height: 0;
        margin-bottom: 0;
        padding: 0;
        border-width: 0;
        visibility: hidden;
    }
}

.toast-icon {
    flex-shrink: 0;
    width: 1.25rem;
    height: 1.25rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: var(--text-xs);
}

.toast-content {
    flex: 1;
    min-width: 0;
}

.toast-title {
    font-weight: 600;
    font-size: var(--text-sm);
    margin-bottom: 0.0625rem;
}

.toast-message {
    font-size: var(--text-xs);
    color: var(--color-gray-500);
}

.toast-success .toast-icon { color: var(--color-success); }
.toast-error .toast-icon { color: var(--color-danger); }
.toast-warning .toast-icon { color: var(--color-warning); }
.toast-info .toast-icon { color: var(--color-info); }

/* --------------------------------------------------------------------------
 * 14. PAGINATION
 * -------------------------------------------------------------------------- */

.pagination {
    display: inline-flex;
    align-items: center;
    border: 1px solid var(--color-gray-300);
}

.page-item {
    display: flex;
}

.page-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 2.25rem;
    height: 2.25rem;
    padding: 0 var(--space-3);
    font-size: var(--text-xs);
    font-weight: 600;
    font-family: var(--font-mono);
    color: var(--color-gray-600);
    background-color: var(--color-white);
    border-right: 1px solid var(--color-gray-200);
    transition: background-color var(--transition-fast), color var(--transition-fast);
}

.page-item:last-child .page-link {
    border-right: none;
}

.page-link:hover:not(.is-active):not(.is-disabled) {
    background-color: var(--color-gray-50);
    color: var(--color-black);
}

.page-link.is-active {
    background-color: var(--color-brand);
    color: var(--color-white);
}

.page-link.is-disabled {
    color: var(--color-gray-300);
    cursor: not-allowed;
}

/* --------------------------------------------------------------------------
 * 15. FOOTER
 * -------------------------------------------------------------------------- */

.site-footer {
    margin-top: auto;
    border-top: 1px solid var(--color-gray-200);
    background-color: var(--color-off-white);
}

.site-footer .app-container {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-6);
    padding-top: var(--space-10);
    padding-bottom: var(--space-10);
}

@media (min-width: 768px) {
    .site-footer .app-container {
        grid-template-columns: 1fr auto;
        align-items: start;
    }
}

.footer-brand {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.footer-brand-name {
    font-family: var(--font-display);
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--color-black);
    letter-spacing: var(--tracking-tight);
}

.footer-brand-desc {
    font-size: var(--text-xs);
    color: var(--color-gray-400);
    max-width: 28rem;
    line-height: var(--leading-relaxed);
}

.footer-meta {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
    font-size: var(--text-xs);
    color: var(--color-gray-400);
}

@media (min-width: 768px) {
    .footer-meta {
        text-align: right;
    }
}

.footer-meta-item {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-family: var(--font-mono);
    letter-spacing: var(--tracking-wide);
}

@media (min-width: 768px) {
    .footer-meta-item {
        justify-content: flex-end;
    }
}

.footer-copyright {
    padding-top: var(--space-5);
    padding-bottom: var(--space-5);
    border-top: 1px solid var(--color-gray-200);
    font-size: var(--text-xs);
    color: var(--color-gray-400);
}

/* --------------------------------------------------------------------------
 * 16. HOME / HERO
 * -------------------------------------------------------------------------- */

.hero-section {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-12);
}

@media (min-width: 1024px) {
    .hero-section {
        grid-template-columns: 1fr 22rem;
        gap: var(--space-16);
        align-items: start;
    }
}

.hero-content {
    display: flex;
    flex-direction: column;
}

.hero-eyebrow {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    font-size: var(--text-xs);
    font-weight: 600;
    font-family: var(--font-mono);
    color: var(--color-brand);
    letter-spacing: var(--tracking-wider);
    text-transform: uppercase;
    margin-bottom: var(--space-6);
}

.hero-eyebrow::before {
    content: '';
    display: block;
    width: 1.5rem;
    height: 1.5px;
    background-color: var(--color-brand);
}

.hero-title {
    font-family: var(--font-display);
    font-size: var(--text-4xl);
    font-weight: 700;
    line-height: var(--leading-tight);
    letter-spacing: var(--tracking-tight);
    color: var(--color-black);
    margin-bottom: var(--space-5);
}

@media (min-width: 768px) {
    .hero-title {
        font-size: var(--text-5xl);
    }
}

.hero-subtitle {
    font-size: var(--text-lg);
    color: var(--color-gray-500);
    max-width: 32rem;
    line-height: var(--leading-relaxed);
    margin-bottom: var(--space-8);
}

.hero-actions {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    margin-bottom: var(--space-10);
}

/* Pitch line — compact value props under CTA */
.home-pitch {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--space-3);
    font-size: var(--text-xs);
    color: var(--color-gray-400);
    font-weight: 500;
}

.home-pitch-dot {
    width: 3px;
    height: 3px;
    border-radius: 50%;
    background: var(--color-gray-300);
    flex-shrink: 0;
}

/* Category sidebar */
.category-sidebar {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

@media (max-width: 1023px) {
    .category-sidebar {
        display: grid;
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 640px) {
    .category-sidebar {
        grid-template-columns: 1fr;
    }
}

/* --------------------------------------------------------------------------
 * 17. RESPONSIVE HELPERS
 * -------------------------------------------------------------------------- */

@media (max-width: 640px) {
    .page-title {
        font-size: var(--text-2xl);
    }

    .modal {
        max-width: none;
    }

    .toast-container {
        left: var(--space-4);
        right: var(--space-4);
        max-width: none;
    }

}