@import url('https://fonts.googleapis.com/css2?family=Staatliches&display=swap');
@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;700&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans:ital,wght@0,400;0,500;0,700;1,400&subset=cyrillic&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Oswald:wght@400;500;700&display=swap');

/* === CSS Custom Properties === */
:root {
    --bg: #181818;
    --bg-card: #222;
    --bg-card-hover: #282828;
    --bg-input: #181818;
    --bg-formula: #1e1e1e;
    --bg-result: #1a1a2e;
    --border: #333;
    --border-light: #444;
    --text: #eee;
    --text-secondary: #ccc;
    --text-muted: #888;
    --text-faint: #666;
    --accent: #ffb300;
    --green: #4ade80;
    --red: #f87171;
    --blue: #60a5fa;
    --shadow: 0 2px 16px rgba(0,0,0,0.3);
}

/* === Base reset & typography === */
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    background: var(--bg);
    color: var(--text);
    font-family: 'DM Sans', 'Segoe UI', Arial, sans-serif;
    line-height: 1.6;
}
a { color: var(--accent); }
h1, h2 {
    font-family: 'Staatliches', sans-serif;
    letter-spacing: 4px;
}

/* === Header & nav === */
.header { text-align: center; padding: 24px 16px 0; }
.header h1 a { color: var(--text); text-decoration: none; }
.header h1 a:hover { color: var(--accent); text-decoration: underline; }
.header h1 a:first-child:hover { color: var(--text); }
hr { border-color: var(--border); margin: 16px 0; }

/* === Layout === */
.container { max-width: 700px; margin: 0 auto; padding: 0 20px 80px; }
h2 { margin: 28px 0 12px; font-size: 1.5em; }
p { margin: 8px 0; color: var(--text-secondary); }

/* === Formula box === */
.formula {
    color: #aaa;
    font-family: monospace;
    background: var(--bg-formula);
    padding: 12px 16px;
    border-radius: 6px;
    margin: 12px 0;
    border-left: 3px solid var(--accent);
}

/* === Example block (shadow instead of flat border) === */
.example {
    background: var(--bg-card);
    border: 1px solid rgba(255,255,255,0.06);
    box-shadow: var(--shadow);
    border-radius: 8px;
    padding: 16px;
    margin: 16px 0;
    font-size: 0.95em;
    line-height: 1.7;
}
.example .label { color: var(--text-muted); }
.example .val { color: var(--accent); font-weight: bold; }

/* === Tip box === */
.tip {
    background: var(--bg-result);
    border: 1px solid rgba(255,255,255,0.06);
    box-shadow: var(--shadow);
    padding: 14px;
    color: #aab;
    border-radius: 8px;
    margin: 12px 0;
    font-size: 0.9em;
}

/* === Calculator === */
.calc {
    background: var(--bg-card);
    border: 1px solid rgba(255,255,255,0.06);
    box-shadow: var(--shadow);
    border-radius: 12px;
    padding: 24px;
    margin: 24px 0;
}
.calc-row { display: flex; gap: 16px; margin: 12px 0; }
.calc-field { flex: 1; }
.calc-field label { display: block; color: var(--text-muted); font-size: 0.85em; margin-bottom: 4px; }
.calc-field input {
    width: 100%;
    background: var(--bg-input);
    border: 1px solid var(--border-light);
    border-radius: 6px;
    color: var(--text);
    padding: 10px 12px;
    font-size: 1em;
    font-family: monospace;
    transition: border-color 0.2s, box-shadow 0.2s;
}
.calc-field input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(255,179,0,0.15);
}

/* === Result box === */
.result {
    margin-top: 16px;
    padding: 16px;
    background: var(--bg-result);
    border: 1px solid rgba(255,255,255,0.06);
    box-shadow: var(--shadow);
    border-radius: 8px;
    display: none;
}
.result.visible { display: block; }
.result-row { display: flex; justify-content: space-between; padding: 4px 0; }
.result-label { color: var(--text-muted); }
.result-value { color: var(--accent); font-weight: bold; font-family: monospace; }

/* === Note box === */
.note {
    margin-top: 12px;
    padding: 12px;
    background: #1a2e1a;
    border: 1px solid #2a4a2a;
    border-radius: 8px;
    font-size: 0.9em;
    color: #8fbc8f;
    display: none;
}
.note.visible { display: block; }

/* === Q&A blocks === */
.qa {
    background: var(--bg-card);
    border: 1px solid rgba(255,255,255,0.06);
    box-shadow: var(--shadow);
    border-radius: 10px;
    padding: 20px;
    margin: 20px 0;
}

/* === Card list (teorie index) === */
.card {
    display: block;
    background: var(--bg-card);
    border: 1px solid rgba(255,255,255,0.06);
    box-shadow: var(--shadow);
    border-radius: 10px;
    padding: 20px 24px;
    transition: border-color 0.2s, background 0.2s, transform 0.2s, box-shadow 0.2s;
}
.card:hover {
    border-color: var(--accent);
    background: var(--bg-card-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 24px rgba(0,0,0,0.4);
}