/**
 * register.courses — Stylesheet
 *
 * CSS custom properties for theming, Inter font, desktop-first responsive.
 * Breakpoints: 1280px, 1024px, 768px, 480px.
 * No frameworks. No preprocessors. Just CSS.
 */

/* ============================================================
   Custom Properties (Design Tokens)
   ============================================================
   Everything themeable lives here. Colors, typography, spacing,
   and layout values are all defined as custom properties so the
   entire visual identity can be adjusted from one place.
   ============================================================ */
:root {
    /* Colors */
    --color-primary: #1a2b4a;
    --color-primary-light: #2a3f6a;
    --color-primary-dark: #0f1a30;
    --color-accent: #3b82f6;
    --color-accent-hover: #2563eb;
    --color-accent-light: #dbeafe;
    --color-success: #16a34a;
    --color-success-bg: #dcfce7;
    --color-warning: #ca8a04;
    --color-warning-bg: #fef9c3;
    --color-error: #dc2626;
    --color-error-bg: #fee2e2;
    --color-info: #2563eb;
    --color-info-bg: #dbeafe;

    --color-background: #ffffff;
    --color-surface: #f8fafc;
    --color-text: #1e293b;
    --color-text-secondary: #64748b;
    --color-text-muted: #94a3b8;
    --color-border: #e2e8f0;
    --color-border-light: #f1f5f9;

    /* Typography */
    --font-family: 'Inter', 'Helvetica Neue', Helvetica, Arial, sans-serif;
    --font-size-xs: 0.75rem;    /* 12px */
    --font-size-sm: 0.875rem;   /* 14px */
    --font-size-base: 1rem;     /* 16px */
    --font-size-lg: 1.125rem;   /* 18px */
    --font-size-xl: 1.25rem;    /* 20px */
    --font-size-2xl: 1.5rem;    /* 24px */
    --font-size-3xl: 1.875rem;  /* 30px */
    --font-size-4xl: 2.25rem;   /* 36px */
    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    /* Spacing */
    --space-xs: 0.25rem;   /* 4px */
    --space-sm: 0.5rem;    /* 8px */
    --space-md: 1rem;      /* 16px */
    --space-lg: 1.5rem;    /* 24px */
    --space-xl: 2rem;      /* 32px */
    --space-2xl: 3rem;     /* 48px */
    --space-3xl: 4rem;     /* 64px */

    /* Layout */
    --container-max: 1200px;
    --container-narrow: 720px;
    --container-padding: var(--space-lg);
    --border-radius: 6px;
    --border-radius-lg: 10px;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
}


/* ============================================================
   Reset / Base
   ============================================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-normal);
    line-height: var(--line-height-normal);
    color: var(--color-text);
    background-color: var(--color-background);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-accent-hover);
}


/* ============================================================
   Typography
   ============================================================ */
h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    color: var(--color-primary);
}

h1 { font-size: var(--font-size-4xl); margin-bottom: var(--space-lg); }
h2 { font-size: var(--font-size-3xl); margin-bottom: var(--space-md); }
h3 { font-size: var(--font-size-2xl); margin-bottom: var(--space-md); }
h4 { font-size: var(--font-size-xl); margin-bottom: var(--space-sm); }

p {
    margin-bottom: var(--space-md);
}

p:last-child {
    margin-bottom: 0;
}


/* ============================================================
   Layout — Container
   ============================================================ */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding-left: var(--container-padding);
    padding-right: var(--container-padding);
}

.container-narrow {
    max-width: var(--container-narrow);
    margin: 0 auto;
    padding-left: var(--container-padding);
    padding-right: var(--container-padding);
}


/* ============================================================
   Site Header
   ============================================================ */
.site-header {
    background-color: var(--color-primary);
    color: #ffffff;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-md);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.site-logo {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: #ffffff;
    letter-spacing: -0.02em;
}

.site-logo:hover {
    color: var(--color-accent);
}

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

.site-nav a {
    color: rgba(255, 255, 255, 0.85);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    transition: color var(--transition-fast);
}

.site-nav a:hover {
    color: #ffffff;
}

.nav-user {
    color: rgba(255, 255, 255, 0.7);
    font-size: var(--font-size-sm);
}


/* ============================================================
   Hamburger Toggle (mobile)
   ============================================================ */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-sm);
}

.hamburger,
.hamburger::before,
.hamburger::after {
    display: block;
    width: 24px;
    height: 2px;
    background-color: #ffffff;
    transition: transform var(--transition-normal);
}

.hamburger {
    position: relative;
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    left: 0;
}

.hamburger::before { top: -7px; }
.hamburger::after  { top: 7px; }

/* Open state — X shape */
.nav-toggle[aria-expanded="true"] .hamburger {
    background-color: transparent;
}

.nav-toggle[aria-expanded="true"] .hamburger::before {
    transform: rotate(45deg);
    top: 0;
}

.nav-toggle[aria-expanded="true"] .hamburger::after {
    transform: rotate(-45deg);
    top: 0;
}


/* ============================================================
   Flash Messages
   ============================================================ */
.flash {
    padding: var(--space-md) 0;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
}

.flash-success { background-color: var(--color-success-bg); color: var(--color-success); }
.flash-error   { background-color: var(--color-error-bg); color: var(--color-error); }
.flash-warning { background-color: var(--color-warning-bg); color: var(--color-warning); }
.flash-info    { background-color: var(--color-info-bg); color: var(--color-info); }


/* ============================================================
   Main Content Area
   ============================================================ */
.site-main {
    flex: 1;
    padding: var(--space-2xl) 0;
}


/* ============================================================
   Site Footer
   ============================================================ */
.site-footer {
    background-color: var(--color-primary);
    color: rgba(255, 255, 255, 0.6);
    padding: var(--space-xl) 0;
    font-size: var(--font-size-sm);
    text-align: center;
}


/* ============================================================
   Buttons
   ============================================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-sm) var(--space-lg);
    font-family: var(--font-family);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    line-height: 1;
    border-radius: var(--border-radius);
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
    white-space: nowrap;
}

.btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

.btn-primary {
    background-color: var(--color-accent);
    color: #ffffff;
    border-color: var(--color-accent);
}

.btn-primary:hover {
    background-color: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
    color: #ffffff;
}

.btn-outline {
    background-color: transparent;
    color: #ffffff;
    border-color: rgba(255, 255, 255, 0.4);
}

.btn-outline:hover {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.8);
    color: #ffffff;
}

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

.btn-lg {
    padding: var(--space-md) var(--space-xl);
    font-size: var(--font-size-base);
}

.btn-block {
    display: flex;
    width: 100%;
}

.btn-success {
    background-color: var(--color-success);
    color: #ffffff;
    border-color: var(--color-success);
}

.btn-danger {
    background-color: var(--color-error);
    color: #ffffff;
    border-color: var(--color-error);
}


/* ============================================================
   Forms
   ============================================================ */
.form-group {
    margin-bottom: var(--space-lg);
}

.form-group label {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    color: var(--color-text);
    margin-bottom: var(--space-xs);
}

.form-control {
    display: block;
    width: 100%;
    padding: var(--space-sm) var(--space-md);
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    color: var(--color-text);
    background-color: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-control:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-accent-light);
}

.form-control::placeholder {
    color: var(--color-text-muted);
}

textarea.form-control {
    resize: vertical;
    min-height: 100px;
}

select.form-control {
    cursor: pointer;
}

.form-hint {
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    margin-top: var(--space-xs);
}

.form-errors {
    background-color: var(--color-error-bg);
    color: var(--color-error);
    padding: var(--space-md);
    border-radius: var(--border-radius);
    margin-bottom: var(--space-lg);
    font-size: var(--font-size-sm);
}

.form-errors ul {
    margin: 0;
    padding-left: var(--space-lg);
}

.form-errors li {
    margin-bottom: var(--space-xs);
}

.form-errors li:last-child {
    margin-bottom: 0;
}


/* ============================================================
   Cards
   ============================================================ */
.card {
    background-color: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: var(--space-xl);
    box-shadow: var(--shadow-sm);
}

.card-header {
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-lg);
    border-bottom: 1px solid var(--color-border-light);
}

.card-title {
    font-size: var(--font-size-xl);
    margin-bottom: 0;
}


/* ============================================================
   Auth Pages (login, register, etc.)
   ============================================================ */
.auth-page {
    display: flex;
    justify-content: center;
    padding-top: var(--space-3xl);
}

.auth-card {
    width: 100%;
    max-width: 440px;
}

.auth-card .card-header {
    text-align: center;
}

.auth-footer {
    text-align: center;
    margin-top: var(--space-lg);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}


/* ============================================================
   Grid Layout
   ============================================================ */
.grid {
    display: grid;
    gap: var(--space-lg);
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }


/* ============================================================
   Tables
   ============================================================ */
.table-wrap {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
}

th, td {
    padding: var(--space-sm) var(--space-md);
    text-align: left;
    border-bottom: 1px solid var(--color-border-light);
}

th {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

tr:hover {
    background-color: var(--color-surface);
}


/* ============================================================
   Badges / Labels
   ============================================================ */
.badge {
    display: inline-block;
    padding: 2px var(--space-sm);
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-semibold);
    border-radius: 999px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.badge-success { background-color: var(--color-success-bg); color: var(--color-success); }
.badge-warning { background-color: var(--color-warning-bg); color: var(--color-warning); }
.badge-error   { background-color: var(--color-error-bg); color: var(--color-error); }
.badge-info    { background-color: var(--color-info-bg); color: var(--color-info); }


/* ============================================================
   Utility Classes
   ============================================================ */
.text-center   { text-align: center; }
.text-right    { text-align: right; }
.text-muted    { color: var(--color-text-secondary); }
.text-small    { font-size: var(--font-size-sm); }
.mt-0  { margin-top: 0; }
.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mb-0  { margin-bottom: 0; }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }


/* ============================================================
   Responsive — 1024px
   ============================================================ */
@media (max-width: 1024px) {
    .grid-3 { grid-template-columns: repeat(2, 1fr); }
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
}


/* ============================================================
   Responsive — 768px (tablet)
   ============================================================ */
@media (max-width: 768px) {
    :root {
        --container-padding: var(--space-md);
    }

    /* Show hamburger, hide nav by default */
    .nav-toggle {
        display: block;
    }

    .site-nav {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background-color: var(--color-primary);
        flex-direction: column;
        padding: var(--space-md);
        gap: var(--space-sm);
        box-shadow: var(--shadow-lg);
    }

    .site-nav.is-open {
        display: flex;
    }

    .site-nav a {
        padding: var(--space-sm) var(--space-md);
        font-size: var(--font-size-base);
    }

    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }

    h1 { font-size: var(--font-size-3xl); }
    h2 { font-size: var(--font-size-2xl); }
}


/* ============================================================
   Responsive — 480px (mobile)
   ============================================================ */
@media (max-width: 480px) {
    :root {
        --container-padding: var(--space-sm);
    }

    .card {
        padding: var(--space-md);
    }

    .btn-lg {
        padding: var(--space-sm) var(--space-lg);
    }
}