:root {
    /* Cole Nussbaumer palette */
    --deep-blue: #1F4E79;      /* Tựa như chữ “data” trên bìa */
    --slate-blue: #4A6FA5;     /* Màu nhạt hơn cho icon / accents */
    --light-bg: #F7F9FA;       /* Nền sáng premium */
    --white: #FFFFFF;
    --grey: #D9E1E8;           /* Viền & background subtle */
    --dark-grey: #2E3B4E;      /* Text đậm, sang trọng */

    /* Shadows nhẹ theo tông xanh của sách */
    --soft-shadow: 0 6px 16px rgba(31, 78, 121, 0.08);
    --soft-shadow-hover: 0 10px 22px rgba(31, 78, 121, 0.15);

    /* Typography */
    --hero-title: 32px;
    --title: 30px;
    --subtitle: 15px;
    --card-title: 18px;
    --text: 15px;
    --text-small: 14px;

    --radius: 16px;
}


/* ---------- GLOBAL ---------- */
body {
    margin: 0;
    font-family: system-ui, sans-serif;
    background: white;
    transition: background 0.3s ease, color 0.3s ease;
}

/* ---------- HEADER ---------- */
.main-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    padding: 30px 70px 10px;
}

.name-title {
    font-size: 32px;
    margin: 0;
    color: var(--deep-blue);
}

.tagline {
    margin-top: 6px;
    font-size: 15px;
    color: var(--dark-grey);
    line-height: 1.4;
}

.tagline .sub {
    font-size: 14px;
}

/* HEADER TEXT */

.name-title {
    font-size: 42px;
    font-weight: 700;
    margin: 0 0 0px;
    color: #1F4E79;
}

.tagline {
    font-size: 20px;
    font-weight: 600;
    color: #1F4E79;
    margin: 0 0 6px;
}

.subline {
    max-width: 400px;          /* giúp văn bản không bị quá dài */
    line-height: 1.45;
    font-size: 14px;
    color: #4A5568;            /* muted – sang hơn */
    margin-top: 0px;
}

.header-right a {
    margin-left: 28px;
    text-decoration: none;
    font-size: 16px;
    color: var(--deep-blue);
    font-weight: 600;
}

.resume-btn {
    border-bottom: 2px solid var(--deep-blue);
}

/* ---------- PROJECTS SECTION ---------- */
.projects-section {
    padding: 10px 70px 60px;
}

.projects-title {
    font-size: 25px;
    color: var(--deep-blue);
}

.projects-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 22px;
    margin-top: 20px;
}

h2 {
    margin-top: 0px;   
}

.projects-title {
    margin-top: 0px;   
}

/* ---------- NEW PROJECT CARD ---------- */
.project-card-new {
    background: var(--white);
    border-radius: 14px;
    border: 1px solid var(--grey);
    box-shadow: var(--soft-shadow);
    padding: 14px;
    display: flex;
    flex-direction: column;
    height: 280px;
}

.project-img-new {
    width: 100%;
    height: auto;
    object-fit: contain;
    border-radius: 8px;
}

.skills-row {
    margin: 10px 0 8px;
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.skill-badge {
    background: #1F4E79;     /* xanh cố định */
    color: #FFFFFF;          /* chữ trắng */
    padding: 4px 10px;
    border-radius: 999px;
    font-size: 11px;
    font-weight: 600;
    border: none;
}


.project-desc {
    font-size: 13px;
    color: var(--dark-grey);
    flex-grow: 1;
}

.learn-more {
    font-size: 13px;
    font-weight: 600;
    color: var(--deep-blue);
    text-decoration: none;
    cursor: pointer;
}

/* ---------- DARK MODE ---------- */
.dark-mode {
    background: #0F1B2B;
    color: #f5f5f5;
}

.dark-mode .name-title,
.dark-mode .projects-title {
    color: white;
}

.dark-mode .tagline {
    color: #cbd7e1;
}

.dark-mode .header-right a {
    color: #e0ecff;
}

.dark-mode .resume-btn {
    border-color: #e0ecff;
}

.dark-mode .project-card-new {
    background: #14273D;
    border-color: #1f3a52;
}

.dark-mode .project-desc {
    color: #cbd7e1;
}

.dark-mode .learn-more {
    color: #e0ecff;
}

/* ---------- DARK MODE TOGGLE BUTTON ---------- */
.toggle-btn {
    position: fixed;
    top: 20px;
    right: 20px;
    background: transparent;
    border: none;
    border-radius: 50%;
    padding: 8px;
    cursor: pointer;
    z-index: 1000;
    transition: all 0.25s ease;
}

.toggle-btn .material-symbols-rounded {
    font-size: 20px;
    color: var(--dark-grey);
    transition: color 0.25s ease;
}

.dark-mode .toggle-btn .material-symbols-rounded {
    color: white;
}