/* ============================================
   StudentTools Hub — Light Clean Theme
   Inspired by modern educational tools
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=JetBrains+Mono:wght@400;500;600&display=swap');

:root {
    /* Primary - Indigo */
    --primary: #4f46e5;
    --primary-light: #6366f1;
    --primary-lighter: #818cf8;
    --primary-bg: #eef2ff;
    --primary-bg2: #e0e7ff;
    --primary-shadow: rgba(79,70,229,0.25);

    /* Accent */
    --accent: #10b981;
    --accent-bg: #ecfdf5;
    --danger: #ef4444;
    --danger-bg: #fef2f2;
    --warning: #f59e0b;
    --warning-bg: #fffbeb;
    --info: #3b82f6;

    /* Backgrounds */
    --bg: #f8fafc;
    --bg-white: #ffffff;
    --bg-section: #f1f5f9;

    /* Text */
    --text: #111827;
    --text-secondary: #4b5563;
    --text-muted: #6b7280;
    --text-light: #9ca3af;

    /* Borders */
    --border: #e5e7eb;
    --border-light: #f3f4f6;
    --border-hover: #d1d5db;

    /* Shadows */
    --shadow-xs: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);

    /* Radius */
    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 16px;
    --radius-full: 9999px;

    /* Font */
    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
}

*, *::before, *::after { margin:0; padding:0; box-sizing:border-box; }
html { scroll-behavior:smooth; font-size:16px; -webkit-font-smoothing:antialiased; }

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    min-height: 100vh;
}

a { color: var(--primary); text-decoration:none; transition:color .2s; }
a:hover { color: var(--primary-light); text-decoration:underline; }
img { max-width:100%; display:block; }
strong { font-weight:600; }

.container { max-width:1200px; margin:0 auto; padding:0 20px; }

/* ============================================
   NAVBAR — White, Fixed
   ============================================ */
.navbar {
    position:fixed; top:0; left:0; right:0; z-index:1000;
    background: var(--bg-white);
    border-bottom: 1px solid var(--border);
    height: 64px;
    box-shadow: var(--shadow-xs);
}
.nav-inner {
    max-width:1200px; margin:0 auto; padding:0 20px;
    display:flex; align-items:center; justify-content:space-between; height:64px;
}
.nav-logo {
    display:flex; align-items:center; gap:8px;
    font-weight:800; font-size:1.2rem; text-decoration:none; color:var(--text);
}
.nav-logo:hover { color:var(--text); text-decoration:none; }
.nav-logo-icon {
    width:32px; height:32px; border-radius:8px;
    background: linear-gradient(135deg, var(--primary), var(--primary-lighter));
    display:flex; align-items:center; justify-content:center;
    color:#fff; font-size:.85rem; font-weight:700;
}
.nav-logo-text {
    background: linear-gradient(135deg, var(--primary), var(--primary-lighter));
    -webkit-background-clip:text; -webkit-text-fill-color:transparent; background-clip:text;
}

.nav-links {
    list-style:none; display:flex; gap:2px; align-items:center;
}
.nav-links a {
    padding:8px 14px; border-radius:var(--radius-sm); font-size:.875rem; font-weight:500;
    color:var(--text-secondary); text-decoration:none; transition:all .15s;
}
.nav-links a:hover { color:var(--primary); background:var(--primary-bg); text-decoration:none; }
.nav-links a.active { color:var(--primary); background:var(--primary-bg); font-weight:600; }

.nav-toggle {
    display:none; flex-direction:column; gap:5px;
    background:none; border:1px solid var(--border); border-radius:var(--radius-sm);
    cursor:pointer; padding:8px; transition:all .2s;
}
.nav-toggle:hover { border-color:var(--primary); }
.nav-toggle span { display:block; width:18px; height:2px; background:var(--text-secondary); border-radius:2px; transition:all .3s; }
.nav-toggle.open span:nth-child(1) { transform:rotate(45deg) translate(4px,4px); }
.nav-toggle.open span:nth-child(2) { opacity:0; }
.nav-toggle.open span:nth-child(3) { transform:rotate(-45deg) translate(5px,-5px); }

/* ============================================
   TWO-COLUMN LAYOUT
   ============================================ */
.page-content { padding-top:84px; padding-bottom:60px; }
.two-col { display:grid; grid-template-columns:1fr 340px; gap:28px; align-items:start; }
.main-col { min-width:0; }
.sidebar { position:sticky; top:84px; }

/* ============================================
   CARDS
   ============================================ */
.card {
    background: var(--bg-white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    box-shadow: var(--shadow-sm);
    margin-bottom: 24px;
}
.card h2 {
    font-size:1.35rem; font-weight:700; color:var(--text); margin-bottom:14px; line-height:1.3;
}
.card h3 { font-size:1.1rem; font-weight:600; margin-bottom:10px; }
.card p { color:var(--text-secondary); margin-bottom:12px; line-height:1.75; }
.card p:last-child { margin-bottom:0; }

/* ============================================
   CALCULATOR CARD
   ============================================ */
.calc-card {
    background: var(--bg-white);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-md);
    margin-bottom: 28px;
}
.calc-title { font-size:1.5rem; font-weight:800; color:var(--primary); margin-bottom:4px; }
.calc-subtitle { color:var(--text-muted); font-size:.92rem; margin-bottom:20px; }

/* Country/Scale Selector */
.scale-selector { margin-bottom:20px; }
.scale-selector label { display:block; font-weight:600; font-size:.88rem; margin-bottom:6px; color:var(--text); }
.scale-select {
    width:100%; padding:10px 14px; border:2px solid var(--border);
    border-radius:var(--radius-sm); font-family:var(--font); font-size:.9rem;
    color:var(--text); background:var(--bg-white); cursor:pointer;
    transition:border-color .2s; appearance:auto;
}
.scale-select:focus { outline:none; border-color:var(--primary); box-shadow:0 0 0 3px var(--primary-bg); }

/* Usage Example Box */
.usage-hint {
    background:var(--primary-bg); border:1px solid var(--primary-bg2);
    border-radius:var(--radius-sm); padding:14px 18px;
    margin-bottom:20px; display:flex; align-items:center; gap:10px;
}
.usage-hint-icon { font-size:1.2rem; }
.usage-hint p { margin:0; font-size:.85rem; color:var(--primary); font-weight:500; }

/* Semester Input Headers */
.sem-input-header {
    display:grid; grid-template-columns:1fr 1fr 40px; gap:12px;
    padding:0 0 8px; font-weight:600; font-size:.8rem; color:var(--text-muted);
    text-transform:uppercase; letter-spacing:.5px;
}

/* Semester Row */
.sem-row {
    display:grid; grid-template-columns:1fr 1fr 40px; gap:12px;
    margin-bottom:10px; align-items:center; animation: slideIn .25s ease both;
}
.sem-row input {
    width:100%; padding:10px 14px; border:2px solid var(--border);
    border-radius:var(--radius-sm); font-family:var(--font); font-size:.9rem;
    color:var(--text); background:var(--bg-white); transition:border-color .2s;
}
.sem-row input:focus { outline:none; border-color:var(--primary); box-shadow:0 0 0 3px var(--primary-bg); }
.sem-row input::placeholder { color:var(--text-light); }
.sem-row .btn-del-row {
    width:38px; height:38px; border:2px solid var(--border); border-radius:var(--radius-sm);
    background:var(--bg-white); cursor:pointer; display:flex; align-items:center; justify-content:center;
    color:var(--text-light); font-size:1rem; transition:all .15s;
}
.sem-row .btn-del-row:hover { border-color:var(--danger); color:var(--danger); background:var(--danger-bg); }

@keyframes slideIn { from{opacity:0;transform:translateY(-8px)} to{opacity:1;transform:translateY(0)} }

/* Calculator Buttons */
.calc-btns { display:flex; gap:10px; margin-top:18px; flex-wrap:wrap; }

.btn {
    display:inline-flex; align-items:center; justify-content:center; gap:6px;
    padding:10px 22px; border-radius:var(--radius-sm); font-weight:600; font-size:.88rem;
    cursor:pointer; border:2px solid transparent; text-decoration:none;
    font-family:var(--font); transition:all .2s;
}
.btn-primary { background:var(--primary); color:#fff; border-color:var(--primary); }
.btn-primary:hover { background:#4338ca; border-color:#4338ca; box-shadow:0 4px 14px var(--primary-shadow); transform:translateY(-1px); color:#fff; text-decoration:none; }
.btn-outline { background:var(--bg-white); color:var(--primary); border-color:var(--primary); }
.btn-outline:hover { background:var(--primary-bg); text-decoration:none; }
.btn-danger-outline { background:var(--bg-white); color:var(--danger); border-color:var(--danger); }
.btn-danger-outline:hover { background:var(--danger-bg); text-decoration:none; }
.btn-ghost { background:transparent; color:var(--text-secondary); border-color:var(--border); }
.btn-ghost:hover { border-color:var(--text-muted); background:var(--bg); text-decoration:none; }
.btn-accent { background:var(--accent); color:#fff; border-color:var(--accent); }
.btn-accent:hover { background:#059669; text-decoration:none; color:#fff; }
.btn-lg { padding:12px 28px; font-size:.95rem; }
.btn-full { width:100%; }
.btn-sm { padding:7px 14px; font-size:.82rem; }

/* Result Box */
.result-box {
    margin-top:22px; padding:24px; border-radius:var(--radius);
    text-align:center; display:none; animation:slideIn .3s both;
}
.result-box.show { display:block; }
.result-box.excellent { background:var(--accent-bg); border:2px solid #a7f3d0; }
.result-box.good { background:var(--primary-bg); border:2px solid var(--primary-bg2); }
.result-box.average { background:var(--warning-bg); border:2px solid #fde68a; }
.result-box.below { background:var(--danger-bg); border:2px solid #fecaca; }
.result-label { display:block; font-size:.78rem; font-weight:600; text-transform:uppercase; letter-spacing:1px; color:var(--text-muted); margin-bottom:4px; }
.result-num { font-size:2.8rem; font-weight:900; font-family:var(--font-mono); margin:4px 0; }
.result-num.c-green { color:#059669; }
.result-num.c-indigo { color:var(--primary); }
.result-num.c-orange { color:#d97706; }
.result-num.c-red { color:var(--danger); }
.result-sub { color:var(--text-secondary); font-size:.88rem; }
.result-badge {
    display:inline-block; padding:4px 16px; border-radius:var(--radius-full);
    font-weight:700; font-size:.8rem; margin-top:8px;
}
.badge-green { background:#d1fae5; color:#065f46; }
.badge-indigo { background:var(--primary-bg2); color:#3730a3; }
.badge-orange { background:#fef3c7; color:#92400e; }
.badge-red { background:#fee2e2; color:#991b1b; }

/* ============================================
   STEPS SECTION
   ============================================ */
.steps-list { list-style:none; padding:0; counter-reset:step; }
.step-item {
    display:flex; gap:16px; padding:18px 0;
    border-bottom:1px solid var(--border-light); align-items:flex-start;
}
.step-item:last-child { border-bottom:none; }
.step-circle {
    width:36px; height:36px; min-width:36px; border-radius:50%;
    background:var(--primary); color:#fff;
    display:flex; align-items:center; justify-content:center;
    font-weight:700; font-size:.85rem; margin-top:2px;
}
.step-item h3 { font-size:1rem; font-weight:700; margin-bottom:4px; color:var(--text); }
.step-item p { color:var(--text-secondary); font-size:.9rem; margin:0; line-height:1.6; }

/* ============================================
   IMPORTANCE CARDS (Why CGPA Matters)
   ============================================ */
.importance-grid { display:grid; grid-template-columns:1fr 1fr; gap:14px; margin:18px 0; }
.imp-card {
    background:var(--bg); border:1px solid var(--border);
    border-radius:var(--radius-sm); padding:18px; transition:all .2s;
}
.imp-card:hover { border-color:var(--primary); box-shadow:var(--shadow-sm); }
.imp-card .imp-icon { font-size:1.5rem; margin-bottom:8px; }
.imp-card h4 { font-size:.92rem; font-weight:700; margin-bottom:4px; }
.imp-card p { font-size:.84rem; color:var(--text-muted); margin:0; line-height:1.55; }

/* ============================================
   TIPS LIST
   ============================================ */
.tips-list { list-style:none; padding:0; margin:14px 0; }
.tips-list li {
    display:flex; gap:10px; padding:10px 0;
    border-bottom:1px solid var(--border-light); font-size:.9rem; color:var(--text-secondary);
}
.tips-list li:last-child { border-bottom:none; }
.tips-list .tip-icon { font-size:1rem; min-width:20px; }

/* ============================================
   SIDEBAR
   ============================================ */
.sidebar-card {
    background:var(--bg-white); border:1px solid var(--border);
    border-radius:var(--radius); padding:22px; box-shadow:var(--shadow-sm);
    margin-bottom:18px;
}
.sidebar-card h3 {
    font-size:.95rem; font-weight:700; color:var(--text);
    padding-bottom:12px; margin-bottom:12px; border-bottom:2px solid var(--primary-bg);
}
.sidebar-links { list-style:none; padding:0; }
.sidebar-links li { margin-bottom:0; }
.sidebar-links a {
    display:flex; align-items:center; gap:8px;
    padding:9px 12px; border-radius:var(--radius-sm);
    font-size:.88rem; color:var(--text-secondary); text-decoration:none; transition:all .15s;
}
.sidebar-links a:hover { background:var(--primary-bg); color:var(--primary); text-decoration:none; }
.sidebar-links .link-icon { font-size:.85rem; }

/* Country Credits Table */
.credits-table { width:100%; border-collapse:collapse; margin:10px 0; }
.credits-table th {
    text-align:left; padding:8px 10px; font-size:.78rem; font-weight:600;
    text-transform:uppercase; letter-spacing:.3px; color:var(--text-muted);
    background:var(--bg); border-bottom:2px solid var(--border);
}
.credits-table td {
    padding:8px 10px; font-size:.85rem; color:var(--text-secondary);
    border-bottom:1px solid var(--border-light);
}
.credits-table tbody tr:hover { background:var(--primary-bg); }

/* ============================================
   FAQ
   ============================================ */
.faq-list { margin-top:14px; }
.faq-item { border:1px solid var(--border); border-radius:var(--radius-sm); margin-bottom:8px; overflow:hidden; }
.faq-item:hover { border-color:var(--border-hover); }
.faq-q {
    display:flex; align-items:center; justify-content:space-between;
    width:100%; padding:14px 18px; background:var(--bg-white);
    border:none; color:var(--text); font-size:.92rem; font-weight:600;
    font-family:var(--font); cursor:pointer; text-align:left; transition:background .15s;
}
.faq-q:hover { background:var(--bg); }
.faq-arrow { font-size:1.2rem; color:var(--text-light); transition:transform .3s; }
.faq-a { max-height:0; overflow:hidden; transition:max-height .35s ease; }
.faq-a-inner { padding:0 18px 16px; color:var(--text-secondary); line-height:1.75; font-size:.9rem; }
.faq-item.open .faq-arrow { transform:rotate(45deg); color:var(--primary); }
.faq-item.open .faq-a { max-height:500px; }
.faq-item.open .faq-q { background:var(--primary-bg); color:var(--primary); }

/* ============================================
   CTA BANNER
   ============================================ */
.cta-banner {
    background: linear-gradient(135deg, var(--primary), var(--primary-lighter));
    border-radius:var(--radius-lg); padding:32px; text-align:center;
    margin:28px 0; color:#fff;
}
.cta-banner h3 { font-size:1.3rem; font-weight:800; margin-bottom:8px; }
.cta-banner p { opacity:.9; font-size:.95rem; margin-bottom:18px; }
.cta-banner .btn { background:#fff; color:var(--primary); border-color:#fff; font-weight:700; }
.cta-banner .btn:hover { background:var(--primary-bg); box-shadow:0 4px 20px rgba(0,0,0,.15); }

/* ============================================
   FOOTER
   ============================================ */
.footer {
    background:var(--bg-white); border-top:1px solid var(--border);
    padding:48px 0 20px;
}
.footer-grid { display:grid; grid-template-columns:2fr 1fr 1fr; gap:36px; margin-bottom:32px; }
.footer-brand p { color:var(--text-muted); font-size:.85rem; margin-top:10px; line-height:1.6; }
.footer-col h4 { font-size:.8rem; font-weight:700; text-transform:uppercase; letter-spacing:1px; color:var(--text-muted); margin-bottom:14px; }
.footer-col ul { list-style:none; }
.footer-col li { margin-bottom:8px; }
.footer-col a { color:var(--text-secondary); font-size:.88rem; text-decoration:none; }
.footer-col a:hover { color:var(--primary); text-decoration:none; }
.footer-bottom { padding-top:18px; border-top:1px solid var(--border); text-align:center; }
.footer-bottom p { color:var(--text-light); font-size:.8rem; }

/* ============================================
   TOOL PAGES
   ============================================ */
.tool-page-header {
    padding:84px 0 20px; background:var(--bg-white);
    border-bottom:1px solid var(--border);
}
.tool-page-header h1 { font-size:1.6rem; font-weight:800; color:var(--primary); margin-bottom:6px; }
.tool-page-header p { color:var(--text-muted); font-size:.95rem; }

.tool-page-body { padding:28px 0 60px; }

/* Simple tool cards for sub-pages */
.simple-tool-card {
    background:var(--bg-white); border:1px solid var(--border);
    border-radius:var(--radius-lg); padding:28px; box-shadow:var(--shadow-md);
    max-width:680px; margin:0 auto;
}
.simple-tool-card h2 { font-size:1.2rem; font-weight:700; margin-bottom:14px; color:var(--text); }
.input-group { margin-bottom:14px; }
.input-group label { display:block; font-weight:600; font-size:.88rem; margin-bottom:5px; color:var(--text); }
.input-field {
    width:100%; padding:10px 14px; border:2px solid var(--border);
    border-radius:var(--radius-sm); font-family:var(--font); font-size:.9rem;
    color:var(--text); transition:border-color .2s;
}
.input-field:focus { outline:none; border-color:var(--primary); box-shadow:0 0 0 3px var(--primary-bg); }
.input-field::placeholder { color:var(--text-light); }
.input-row { display:grid; grid-template-columns:1fr 1fr; gap:14px; }

/* Timer */
.timer-display {
    font-size:4.5rem; font-weight:900; font-family:var(--font-mono);
    color:var(--primary); text-align:center; margin:16px 0;
}
.timer-btns { display:flex; gap:10px; justify-content:center; flex-wrap:wrap; }
.mode-btns { display:flex; gap:6px; justify-content:center; margin-bottom:20px; flex-wrap:wrap; }
.mode-btns .btn.active { background:var(--primary); color:#fff; border-color:var(--primary); }

.timer-ring-wrap { display:flex; justify-content:center; margin:10px 0; }
.timer-ring { transform:rotate(-90deg); }
.timer-ring-bg { fill:none; stroke:var(--border); stroke-width:6; }
.timer-ring-progress { fill:none; stroke:var(--primary); stroke-width:6; stroke-linecap:round; transition:stroke-dashoffset .5s; }

.timer-stats {
    display:flex; justify-content:center; gap:32px; flex-wrap:wrap;
    margin-top:22px; padding-top:18px; border-top:1px solid var(--border);
}
.timer-stat { text-align:center; }
.timer-stat-num { display:block; font-size:1.4rem; font-weight:800; color:var(--primary); font-family:var(--font-mono); }
.timer-stat-label { font-size:.72rem; color:var(--text-light); text-transform:uppercase; letter-spacing:.5px; }

/* ============================================
   RESPONSIVE
   ============================================ */
@media(max-width:1024px) {
    .two-col { grid-template-columns:1fr; }
    .sidebar { position:static; }
    .footer-grid { grid-template-columns:1fr 1fr; }
}

@media(max-width:768px) {
    .nav-toggle { display:flex; }
    .nav-links {
        position:fixed; top:64px; left:0; right:0;
        background:var(--bg-white);
        flex-direction:column; padding:12px;
        border-bottom:1px solid var(--border);
        box-shadow:var(--shadow-md);
        transform:translateY(-110%); opacity:0; visibility:hidden;
        transition:all .3s ease; z-index:999;
    }
    .nav-links.open { transform:translateY(0); opacity:1; visibility:visible; }
    .nav-links a { padding:12px 14px; font-size:.92rem; }

    .calc-card { padding:22px; }
    .sem-row { grid-template-columns:1fr 1fr 36px; gap:8px; }
    .sem-input-header { grid-template-columns:1fr 1fr 36px; gap:8px; }
    .importance-grid { grid-template-columns:1fr; }
    .footer-grid { grid-template-columns:1fr; gap:24px; }
    .input-row { grid-template-columns:1fr; }
    .calc-btns { flex-direction:column; }
    .calc-btns .btn { width:100%; }
    .timer-display { font-size:3.2rem; }
}

@media(max-width:480px) {
    html { font-size:15px; }
    .calc-card { padding:16px; }
    .card { padding:20px; }
    .sem-row input { padding:9px 10px; font-size:.85rem; }
}

/* Notification Toast */
.toast {
    position:fixed; top:74px; right:16px; z-index:10001;
    padding:12px 18px; border-radius:var(--radius-sm); font-size:.88rem;
    display:flex; align-items:center; gap:8px; font-family:var(--font);
    animation:slideIn .25s both; box-shadow:var(--shadow-md);
}
.toast-error { background:#fef2f2; border:1px solid #fecaca; color:var(--danger); }
.toast-success { background:#ecfdf5; border:1px solid #a7f3d0; color:#059669; }
.toast button { background:none; border:none; color:inherit; cursor:pointer; font-size:1rem; }