:root {
    --sys-font-scale: 100%;
}

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

/* --- Global Font Size Minimums --- */
html, body {
    overflow-x: hidden;
    width: 100%;
    margin: 0;
    padding: 0;
}

html {
    font-size: var(--sys-font-scale);
}

body,
input,
select,
textarea,
button,
.form-control,
.form-select,
.btn {
    font-family: 'Sarabun', sans-serif;
    font-size: 1rem;
}

small,
.small {
    font-size: 0.88rem !important;
}

/* ===== Light Mode — Permanent (Dark Mode Removed) ===== */
:root {
    /* --- Base Palette (Light - Always) --- */
    --sys-bg-body: #f1f5f9;
    --sys-bg-card: #ffffff;
    --sys-bg-sidebar: #ffffff;
    --sys-bg-topbar: rgba(255, 255, 255, 0.97);

    --sys-text-primary: #000000;     /* Absolute Black */
    --sys-text-secondary: #0f172a;   /* Deep Dark Blue/Grey */
    --sys-text-muted: #1e293b;       /* Dark Slate — Clearer */
    --sys-text-faint: #334155;       /* Medium-Dark Blue/Grey */

    --sys-border: rgba(0, 0, 0, 0.08);
    --sys-border-mid: rgba(0, 0, 0, 0.1);

    --sys-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
    --sys-glass-blur: 10px;

    /* --- Brand Colors (Consistent) --- */
    --sys-primary: #dc2626;
    /* Admin Red */
    --sys-secondary: #6366f1;
    /* Student Indigo */
    --sys-accent: #f59e0b;
    /* Mentor Amber */

    /* --- Area-Specific Aliases (Light) --- */
    /* Admin Area */
    --adm-bg-body: var(--sys-bg-body);
    --adm-bg-card: var(--sys-bg-card);
    --adm-bg-sidebar: var(--sys-bg-sidebar);
    --adm-bg-topbar: var(--sys-bg-topbar);
    --adm-text-primary: var(--sys-text-primary);
    --adm-text-secondary: var(--sys-text-secondary);
    --adm-text-muted: var(--sys-text-muted);
    --adm-text-faint: var(--sys-text-faint);
    --adm-border: var(--sys-border);
    --adm-border-mid: var(--sys-border-mid);
    --adm-shadow: var(--sys-shadow);
    --adm-user-bg: #f8fafc;

    /* Student Area */
    --std-bg-body: #f1f5f9;
    --std-bg-card: #ffffff;
    --std-bg-nav: rgba(255, 255, 255, 1);
    --std-text-primary: var(--sys-text-primary);
    --std-text-secondary: var(--sys-text-secondary);
    --std-text-muted: var(--sys-text-muted);
    --std-border: var(--sys-border);
    --std-shadow: var(--sys-shadow);

    /* Mentor Area */
    --mtr-bg-body: #f0f4fa;
    --mtr-bg-card: #ffffff;
    --mtr-text-primary: var(--sys-text-primary);
    --mtr-text-secondary: #1e293b;
    --mtr-text-muted: #334155;
    --mtr-border: rgba(0, 0, 0, 0.12);
}

/* ===== Global Modal Overrides ===== */
/* All modals: static backdrop + minimum XL size */
.modal .modal-dialog {
    max-width: min(1140px, 95vw);
}

.modal .modal-dialog.modal-sm {
    max-width: min(1140px, 95vw);
}

.modal .modal-content {
    background: #ffffff;
    color: #0f172a;
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-radius: 16px;
}

.modal .modal-header {
    border-bottom-color: rgba(0, 0, 0, 0.08);
}

.modal .modal-footer {
    border-top-color: rgba(0, 0, 0, 0.08);
}

/* ===== Global Bootstrap Overrides — Light Mode Only ===== */
.table {
    color: #1e293b;
}

.card {
    background: #ffffff;
    border-color: rgba(0, 0, 0, 0.08);
    color: #1e293b;
}

.form-control,
.form-select {
    background-color: #ffffff;
    border-color: rgba(0, 0, 0, 0.15);
    color: #1e293b;
}

.form-control::placeholder {
    color: #94a3b8;
}

.text-muted {
    color: var(--sys-text-muted) !important;
}

.text-secondary {
    color: var(--sys-text-secondary) !important;
}

.btn-close {
    filter: none;
}

/* ===== Standardized Layout Components ===== */

/* Unified App Header Base */
.app-header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: var(--sys-bg-topbar);
    backdrop-filter: blur(var(--sys-glass-blur));
    -webkit-backdrop-filter: blur(var(--sys-glass-blur));
    border-bottom: 1px solid var(--sys-border);
    padding: 0.75rem 1.25rem;
    transition: all 0.3s ease;
}

.header-container {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    flex-wrap: nowrap; /* Force single row */
    width: 100%;
}

/* Header Sections */
.header-left {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-shrink: 1;
    overflow: hidden;
}

.header-center {
    flex: 1;
    text-align: center;
    display: flex;
    flex-direction: column;
    justify-content: center;
    overflow: hidden;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-shrink: 0;
}

/* Header Title Typography */
.header-title {
    font-size: 1.15rem;
    font-weight: 800;
    color: var(--sys-text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    line-height: 1.2;
}

.header-subtitle {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--sys-text-faint);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Control Groups */
.nav-controls {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: rgba(0, 0, 0, 0.03);
    padding: 4px;
    border-radius: 12px;
    border: 1px solid var(--sys-border);
}

/* Specific Buttons */
.hdr-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.6rem 1rem;
    border-radius: 10px;
    border: 1px solid var(--sys-border);
    background: #fff;
    color: var(--sys-text-secondary);
    font-weight: 700;
    font-size: 0.9rem;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.2s;
    white-space: nowrap;
}

.hdr-btn:hover {
    background: #f8fafc;
    border-color: var(--sys-border-mid);
    transform: translateY(-1px);
}

/* Back Button Specific */
.hdr-btn.back {
    padding: 0.6rem 0.85rem;
}

@media (max-width: 600px) {
    .hdr-btn span { display: none; } /* Hide text on small mobile, show only icon */
    .hdr-btn { padding: 0.6rem; border-radius: 8px; }
    .header-subtitle { display: none; }
    .header-title { font-size: 0.95rem; }
    .app-header { padding: 0.6rem 0.5rem; }
    .header-container { gap: 0.5rem; }
    .header-left img { width: 30px; height: 30px; }
}

@media (max-width: 400px) {
    .header-center { display: none; } /* Hide center info on extremely small screens to save space */
}

/* ===== Standardized Page Container ===== */
.pg-container {
    max-width: 1400px;
    width: 100%;
    margin: 0 auto;
    padding: 1.5rem 1.25rem 5rem;
    overflow-x: hidden;
}

@media (max-width: 768px) {
    .pg-container {
        padding: 1rem 1rem 4rem; /* Increased side padding for edge films */
    }
}

/* ===== Font Controls (Retained for Accessibility) ===== */
.btn-font-adjust {
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-radius: 8px;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--sys-text-secondary);
    font-size: 0.85rem;
    font-weight: 800;
    transition: all 0.2s;
    user-select: none;
}

.btn-font-adjust:hover {
    background: var(--sys-primary, #dc2626);
    color: #fff;
    border-color: var(--sys-primary, #dc2626);
    transform: scale(1.05);
}

.btn-font-adjust.font-scale-reset {
    font-size: 0.95rem;
}

/* High Contrast Adjustments */
.font-scale-down { font-size: 0.75rem; }
.font-scale-up { font-size: 1.1rem; }

/* ===== Universal Modern Footer ===== */
.site-global-footer {
    width: 100%;
    margin-top: 4rem;
    padding: 2.25rem 1rem 2.5rem;
    border-top: 1px solid rgba(0, 0, 0, 0.08);
    background: transparent;
    display: block;
    clear: both;
}

.footer-inner-content {
    max-width: 960px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    gap: 0.75rem;
    font-family: 'Sarabun', sans-serif;
}

.footer-copyright-text {
    font-size: 0.9rem;
    font-weight: 600;
    color: #475569;
    letter-spacing: -0.1px;
    line-height: 1.5;
}

.footer-system-info {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.6rem;
    font-size: 0.85rem;
    color: #64748b;
}

.footer-system-info .system-title {
    font-weight: 600;
    color: #334155;
}

.footer-bullet {
    color: #cbd5e1;
    font-size: 1rem;
    line-height: 1;
}

.dev-by-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.08), rgba(99, 102, 241, 0.1));
    color: #1e40af;
    padding: 0.25rem 0.85rem;
    border-radius: 999px;
    font-size: 0.82rem;
    font-weight: 600;
    border: 1px solid rgba(37, 99, 235, 0.2);
    box-shadow: 0 2px 6px rgba(37, 99, 235, 0.06);
    transition: all 0.25s ease;
}

.dev-by-badge:hover {
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.15), rgba(99, 102, 241, 0.18));
    border-color: rgba(37, 99, 235, 0.35);
    color: #1d4ed8;
    transform: translateY(-1.5px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.15);
}

.footer-action-links {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.6rem;
    margin-top: 0.35rem;
}

.footer-pipe {
    display: none;
}

.footer-nav-btn,
.footer-nav-link {
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    padding: 0.45rem 1rem;
    border-radius: 999px;
    font-size: 0.84rem;
    font-weight: 600;
    text-decoration: none !important;
    background: #ffffff;
    color: #334155;
    border: 1.5px solid #e2e8f0;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.03);
    cursor: pointer;
    transition: all 0.22s cubic-bezier(0.4, 0, 0.2, 1);
    font-family: inherit;
    line-height: 1.3;
}

.footer-nav-btn:hover,
.footer-nav-link:hover {
    background: #ffffff;
    color: #2563eb;
    border-color: #3b82f6;
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(59, 130, 246, 0.14);
}

.footer-nav-btn:active,
.footer-nav-link:active {
    transform: translateY(0);
}