/* Responsive & Themed CSS - Full Repair */

/* 1. Theme Variables */
:root {
    /* Default Dark Theme */
    --bg-color: #0F172A;
    --text-primary: #F8FAFC;
    --text-secondary: #94A3B8;
    --card-bg: #1E293B;
    --border-color: #334155;
    --accent-color: #3B82F6;
    --accent-glow: rgba(59, 130, 246, 0.5);

    --nav-bg: rgba(15, 23, 42, 0.8);
}

[data-theme="light"] {
    --bg-color: #F1F5F9;
    --text-primary: #1E293B;
    --text-secondary: #64748B;
    --card-bg: #FFFFFF;
    --border-color: #E2E8F0;
    --accent-color: #2563EB;
    --accent-glow: rgba(37, 99, 235, 0.3);

    --nav-bg: rgba(255, 255, 255, 0.9);
}

/* Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color 0.3s, color 0.3s;
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    background: var(--nav-bg);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
}

.nav-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
    position: relative;
    padding: 0 1rem;
}

.logo {
    font-weight: 800;
    font-size: 1.5rem;
    color: var(--text-primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
    font-size: 0.95rem;
}

.nav-link:hover,
.nav-link.active-link {
    color: var(--accent-color);
}

/* Theme Toggle Button */
.theme-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 1.2rem;
    cursor: pointer;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
    margin-left: 1rem;
}

.theme-btn:hover {
    background: var(--card-bg);
    transform: rotate(15deg);
}

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1.8rem;
    cursor: pointer;
    z-index: 1001;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    width: 100%;
}

/* Main Content */
/* Main Content */
main {
    flex: 1;
    padding-top: 120px;
    /* Base padding */
    padding-bottom: 4rem;
}

/* Specific page padding override is NOT needed if we set base padding correctly.
   However, let's ensure containers inside main also don't cancel this out. */


/* Specific page padding override is NOT needed if we set base padding correctly.
   However, let's ensure containers inside main also don't cancel this out. */


/* Ad Placeholder - REMOVED / HIDDEN */
.ad-placeholder {
    display: none !important;
}

/* Light Mode Nav Link Fix */
[data-theme="light"] .nav-link {
    color: #475569;
    /* Darker slate for readability on white */
}

[data-theme="light"] .nav-link:hover,
[data-theme="light"] .nav-link.active-link {
    color: var(--accent-color);
}

[data-theme="light"] .logo {
    color: #1e293b;
}

/* Ensure active link is visible in dark mode too */
.nav-link.active-link {
    color: var(--accent-color);
    font-weight: 700;
}



/* Hero Section */
.hero {
    text-align: center;
    padding: 4rem 0;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    font-weight: 800;
}

.hero p {
    color: var(--text-secondary);
    font-size: 1.25rem;
    max-width: 600px;
    margin: 0 auto 2rem;
}

/* Cards & Grid */
.grid {
    display: grid;
    gap: 1.5rem;
}

.exam-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    padding: 2rem 0;
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    padding: 2rem;
    transition: transform 0.2s, box-shadow 0.2s, background-color 0.3s;
    position: relative;
    overflow: hidden;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
    border-color: var(--accent-color);
}

/* Footer */
footer {
    background: var(--card-bg);
    border-top: 1px solid var(--border-color);
    padding: 3rem 0;
    text-align: center;
    color: var(--text-secondary);
}

.footer-links {
    margin-bottom: 1rem;
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
}

.visitor-counter {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: rgba(59, 130, 246, 0.1);
    padding: 0.5rem 1rem;
    border-radius: 99px;
    margin-top: 1rem;
    border: 1px solid rgba(59, 130, 246, 0.2);
    font-size: 0.9rem;
}

.visitor-counter strong {
    color: var(--accent-color);
    font-family: 'Courier New', monospace;
    letter-spacing: 1px;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
    text-decoration: none;
    font-size: 1rem;
}

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

.btn-primary:hover {
    filter: brightness(1.1);
    box-shadow: 0 0 15px var(--accent-glow);
}

.btn-secondary {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--accent-color);
}

/* Modals */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
    z-index: 2000;
}

.modal.active {
    opacity: 1;
    pointer-events: all;
}

.modal-content {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 1.5rem;
    width: 90%;
    max-width: 500px;
    position: relative;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.close-modal {
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
}

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

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 1.5rem;
}

/* --- RESTORED SPECIFIC STYLES --- */

/* Timer / Chronometer */
.timer-container {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 2rem;
    padding: 3rem;
    max-width: 500px;
    margin: 0 auto;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.timer-circle {
    width: 280px;
    height: 280px;
    border-radius: 50%;
    border: 8px solid var(--border-color);
    margin: 2rem auto;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4.5rem;
    font-weight: 700;
    font-variant-numeric: tabular-nums;
    position: relative;
    box-shadow: 0 0 30px rgba(0, 0, 0, 0.2) inset;
    background: rgba(0, 0, 0, 0.1);
}

.timer-controls {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

.timer-btn {
    width: 64px;
    height: 64px;
    border-radius: 50%;
    border: none;
    background: var(--border-color);
    color: var(--text-primary);
    font-size: 1.5rem;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.timer-btn.active {
    background: var(--accent-color);
    color: white;
    box-shadow: 0 0 20px var(--accent-glow);
}

/* Tables (Calendar) */
.table-container {
    overflow-x: auto;
    background: var(--card-bg);
    border-radius: 1rem;
    border: 1px solid var(--border-color);
    margin-bottom: 2rem;
}

table {
    width: 100%;
    border-collapse: collapse;
    min-width: 600px;
    /* Ensure structure on mobile */
}

th,
td {
    padding: 1rem 1.5rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background: rgba(0, 0, 0, 0.2);
    font-weight: 600;
    color: var(--accent-color);
}

tr:hover td {
    background: rgba(255, 255, 255, 0.02);
}

/* Calendar Grid Styles */
.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 0.5rem;
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 1rem;
    border: 1px solid var(--border-color);
}

.calendar-header {
    text-align: center;
    font-weight: 700;
    color: var(--text-secondary);
    padding-bottom: 0.5rem;
}

.calendar-day {
    aspect-ratio: 1;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    padding: 0.5rem;
    position: relative;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
}

.calendar-day:hover:not(.empty) {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--accent-color);
}

.calendar-day.empty {
    border: none;
    cursor: default;
    background: transparent !important;
}

.calendar-day.today {
    background: rgba(59, 130, 246, 0.1);
    border-color: var(--accent-color);
    font-weight: 700;
}

.day-number {
    font-size: 0.9rem;
    margin-bottom: 0.25rem;
}

.day-note-indicator {
    flex: 1;
    font-size: 0.75rem;
    overflow: hidden;
    text-overflow: ellipsis;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 0.25rem;
    padding: 2px 4px;
    border-left: 3px solid transparent;
}


/* --- MOBILE RESPONSIVENESS --- */
@media (max-width: 768px) {

    /* Navbar */
    .mobile-menu-btn {
        display: block;
    }

    .nav-links {
        position: fixed;
        top: 70px;
        left: 0;
        width: 100%;
        background: var(--card-bg);
        flex-direction: column;
        padding: 2rem;
        gap: 1.5rem;
        border-bottom: 1px solid var(--border-color);
        transform: translateY(-150%);
        transition: transform 0.3s ease-in-out;
        z-index: 999;
    }

    .nav-links.active {
        transform: translateY(0);
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    }

    .nav-link {
        font-size: 1.2rem;
        display: block;
        padding: 0.5rem 0;
        border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    }

    /* Typography */
    .hero h1 {
        font-size: 2.5rem;
    }

    .hero p {
        font-size: 1rem;
    }

    /* Grids to Single Column */
    .exam-grid,
    .grid,
    .timer-container {
        width: 100%;
        max-width: 100%;
        padding: 1.5rem;
    }

    /* Container Padding */
    .container {
        padding: 0 1rem;
    }

    /* Timer Specific */
    .timer-circle {
        width: 220px;
        height: 220px;
        font-size: 3.5rem;
    }

    /* BİLSEM Specifics for Mobile */
    .memory-grid {
        grid-template-columns: repeat(4, 1fr) !important;
        gap: 0.25rem !important;
    }

    .memory-card {
        font-size: 1.25rem !important;
        height: 60px;
    }
}